1014. Best Sightseeing Pair

Medium

You are given an integer array values where values[i] represents the value of the ith sightseeing spot. Two sightseeing spots i and j have a distance j - i between them.

The score of a pair (i < j) of sightseeing spots is values[i] + values[j] + i - j: the sum of the values of the sightseeing spots, minus the distance between them.

Return the maximum score of a pair of sightseeing spots.

Example 1:

Input: values = [8,1,5,2,6]
Output:
 11
Explanation:
 i = 0, j = 2, values[i] + values[j] + i - j = 8 + 5 + 0 - 2 = 11

Example 2:

Input: values = [1,2]
Output:
 2

Constraints:

• 2 <= values.length <= 5 * 104

• 1 <= values[i] <= 1000

解題

O(n)

Runtime: 46 ms, faster than 100%

Memory Usage: 7.6 MB, less than 55.26%

func maxScoreSightseeingPair(values []int) int {
    add := make([]int, len(values)) // 儲存 當前最大的 i, values[i] 和
    add[0] = values[0]

    ans := add[0] + values[1] - 1

    for i := 1; i< len(values); i++ {
        add[i] = max(add[i - 1], i + values[i])
        
        if values[i] - i + add[i - 1] > ans {
            ans = values[i] - i + add[i - 1]
        }
    }

    return ans
}

func max(a, b int) int {
    if a > b { return a }
    return b
}